Friday, April 23, 2010

Q: Professor, I pulled my information from thepaleodiet.com and attributed the statement, "Paleo is truly is the world’s healthiest diet," to you, which I doubt is a stretch.

Have you gotten into any of the information about the blood-type-related nutrition info? I've only heard snippets, but I'm curious what an expert thinks of it.

Seth

A: Hi Seth,

Thanks for your support. I am currently completing a paper on nightshades, and when it is done the very next topic in the queue is my critique of the Blood Type Diet, which I have been researching and reading about for the past couple of weeks. Although I don’t want to give away the story line, I can say that the concept of four specific types of diet for the four ABO blood groups (A, B, O & AB) is not supported by the available data. However, having said that, susceptibility to disease, and the robustness of the immune response to pathogens throughout the entire GI tract, is very much related to ABO blood groups. Our group has published at least one paper on the dietary lectin/disease concept and we believe that common dietary lectins may promote certain diseases (allergies, autoimmune disease) while simultaneously promoting chronic low level inflammation. However, little evidence in either humans, animals or tissues point in the direction that dietary lectins elicit disease symptoms exclusively via interaction with ABO antigens. Additionally, of the hundreds of plant lectins that have been identified, only a very select few have been demonstrated to bind gut tissue. Hence, most dietary lectins are benign, simply because they cannot penetrate the gut barrier.

Tuesday, April 20, 2010

Nell Stephenson, Fitness & Nutritional Professional, Ironman Triathlete, and contributor to our newsletter was recently contacted by Details magazine to write up sample menus for endurance athletes: one for a workout day, the other for an off-day from training.

After reading your article on chia seeds, I forwarded the article to Dr. Vlad Vuksan in Canada, one of the leading researchers/promoters of Salba Seeds. After he got your article, he seemed to object that your conclusions apply uniquely to chia seeds generically, but not to Salba Seeds (single variety).

Is such a distinction valid? Wouldn't your conclusions regarding chia seeds apply as well to Salba, a variety of chia?

Thanks for your insights,Frank

A: Hi Frank,

I stand by my conclusions in the newsletter. Until further human trials are completed employing a sample size with sufficient statistical power to resolve these immune system issues, then the potential adverse effects of long term, chronic chia seed consumption may outweigh the potential benefits. I respect Dr. Vukan’s long time collaborative work with David Jenkins at the University of Toronto, particularly in regard to their pioneering work on the glycemic index. I have read both of Dr. Vukan’s recent chia seed papers1, 2, and in neither one do the authors make any distinction between generic Salvia hispanica L. and the trade name (Salba) version of the seed they employed in their two studies. Hence, unless Dr. Vukan and colleagues can show otherwise, the literature results I have uncovered remain unchanged and apply to both Salba and Salvia hispanica L. It should be noted that at least two of the subjects in Dr. Vukan’s first study2 refused to continue because of gastrointestinal side effects.

In regard to Dr. Vukan’s first chia study, Table 1 shows a non-significant decrease (7.0 %) in the treatment group’s CRP and a 32.9 % increase in the control group value. The authors interpret this bi-directional group change in the abstract and elsewhere as a significant reduction (40 + 1.6% p less than 0.04) in CRP. This kind of data reporting is misleading when the treatment group mean change was actually non-significant. Despite ANCOVA adjustment for age, gender and sequence in their repeated measures model, their interpretation of the CRP data is at best misleading but likely incorrect. An additional shortcoming in this study involves the reporting of ALA and EPA data (results p. 2806). Why weren’t the actual plasma concentrations (mean + SD) of both of these fatty acids reported in both the experimental and control group? Given that 2% or less of ALA is chain elongated and desaturated into DHA, the EPA data need further scrutiny. Did the reported % differences for ALA and EPA represent within group differences or factorial differences? These shortcomings potentially invalidate the conclusions of the paper that CRP was reduced. In contrast, Nieman and colleagues3 were unable to replicate Dr. Vukan and colleague’s results in a similar study with a much larger sample size and hence greater statistical power.

Q: Are there any negative effects associated with chia seeds which would make them inappropriate in The Paleo Diet?

Thank you.

A: Good question. I would imagine that many of our readers have never even heard of chia seeds much less eaten them. Chia seeds (Salvia hispanica L.) are a member of the Labiatae plant family and are native to southern Mexico and northern Guatemala. The seeds are small, oval shaped; either black or white colored and resemble sesame seeds. These seeds were cultivated as a food crop for thousands of years in this region by the Aztecs and other native cultures. Chia seeds can be consumed in a variety of ways including roasting and grinding the seeds into a flour known as Chianpinolli which can then become incorporated into tortillas, tamales, and various beverages. The roasted ground seeds were traditionally consumed as a semi-fluid mucilaginous gruel (Pinole) when water is added to the flour. In post-Columbian times the most popular use of chia flour was to make a refreshing beverage in which the ratio of seeds to water is decreased, thereby resulting in a less gelatinous consistency to which lemon, sugar or fruit juice are added. The sticky consistency of chia seed Pinole or chia beverages comes from a clear mucilaginous, polysaccharide gel that remains tightly bound to the seeds. This sticky gel forms a physical barrier which may impair digestion and absorption of fat from the seed4 while also causing a low protein digestibility.

In the past 20 years a revival of interest in chia seeds has occurred primarily because of their high fat content of about 25-39% by weight, of which 50-57% is the therapeutic omega 3 fatty acid and alpha linolenic acid (ALA). In the past 10 years chia seeds have been used as a foodstuff for animals to enrich their eggs and meat with omega 3 fatty acids. So I wholeheartedly approve of feeding chia seeds to animals and then eating the omega 3 fatty acid enriched meat or eggs of these animals.

How about feeding chia seeds to humans – should we consume chia seeds because of their high omega 3 fatty acid (ALA) content? The Table below shows the entire nutrient profile of chia seeds. At least on paper, it would appear that chia seeds are a nutritious food that is not only high in ALA, but also is a good source of protein, fiber, certain B vitamins, calcium, iron and manganese.

Monday, April 5, 2010

Dr. Cordain was a guest on the The Soul's Edge radio program on KKNW Alternative Talk Radio, 1150 AM, in Seattle on March 30. You may listen to an MP3 recording of the interview from our web site. The segment with Dr. Cordain begins at time index 15:23 in the MP3 recording.

Friday, April 2, 2010

Q: Hi there - I have been following a Paleo Diet for a few weeks now and there is no doubt that I feel much better for it. I did not need to lose weight and I always regarded myself as pretty fit and healthy. However, a little while back I developed a troublesome skin condition called Lichen Sclerosis. Have you ever been asked about this condition and suggested dietary changes? I think part of the problem is that the etiology is not fully understood but many doctors seem to think it has an autoimmune component though I have read recent research that suggests oxidative damage plays a part and that antioxidant therapy may be useful in treatment. This condition is supposedly incurable (though manageable with potent steroids) but I'm sure it would give a great many people some comfort if simple dietary changes could help. Would be really great to hear your thoughts.

Simon

A: Dear Simon,

The available evidence indicates that an autoimmune component likely occurs with Lichen Sclerosis (LS). With all autoimmune diseases, an autoantigen (self protein) exists and represents the target protein being attacked by the immune system. About 75 % of LS patients maintain an IgG autoantibody to Extra Cellular Matrix Protein 1 (ECM1)1. Acceleration of ECM1 deposition in dermal (skin) blood vessels may underlie the disease symptoms 2, 3. So the question now arises, what causes an accelerated deposition of ECMI in dermal blood vessels in LS patients? The available evidence indicates that increased concentrations of a ubiquitous enzyme in the body called tissue transglutaminase (TG2) is primarily responsible for excessive ECM1 accumulation3. In medical terms, an increase in a concentration of a substance in the bloodstream by another substance is called "upregulation".

So, in LS patients, an upregulation of TG2 causes an upregulation and increased deposition of ECMI in the skin blood vessels in the affected area of the body. The next question to be posed is, what event or events trigger an upregulation of TG2? When we answer this question, then dietary recommendations advocated by the Paleo Diet will make sense. A storage protein called gliadin which is fournd in wheat, rye, barley and oats is known to upregulate TG2 4-7. Hence grain free diets may prove to be therapeutic for LS patients, although no current randomized controlled trials of this intervention strategy have yet been conducted.

Q:Is Stevia Paleo? I have attempted to find an answer for this and the information I've found is conflicting at best. Please advise!!Jeff

A: Dear Jeff,

There's some scientific evidence to support the notion that Stevia is safe, even in type 2 diabetes patients1, 2. Furthermore, it has been demonstrated to have antihypertensive properties, as shown by Chan et al.3 and a long-term study4. Having said this, I am not aware of any study examining the potential antinutrient (lectins or saponins) content of the plant, hence we do not know the possible adverse effect of consuming this plant on a daily basis. Hunterh-gatherers used to consume a wide range of plants, thereby minimizing the amount of a single bioactive compound ingested and its toxicity. It is known that rotating the kind of plants is a good strategy in order to decrease food allergy and intolerance.

From an evolutionary standpoint we should look at nutrition as "whole food" rather than nutrients per se. The bottom line is that Stevia seems to be safe, but we need more research to rule out possible side effects.